1. Advance Computer Networks:Default Routing And On demand Routing

2. Overview:What is routing?What is default routing?Examples of default routingWhat is On demand routing?Examples of On Demand routingConclusionBibliography 3. Introduction: Process of selecting best paths in anetwork. Routing is performed for many kindsof networks, including thetelephone network (circuit switching), electronic data networks (such asthe Internet), andtransportation networks. The routing process usually directsforwarding on the basis ofrouting tables which maintain arecord of the routes to variousnetwork destinations. 4. What is default routing?Is configured for unknown destinations.Generally used on internet as destinations are unknown. Example: ID on gmail or yahoo, etcConfigured at end points.It is last preferred routing. 5. If there is no static route or learned route, the NetworkLayer checks for a default route. 6. The Role of the Default RouteMaintaining a list of all possible destinationsMaintains memory required to store thousands of IP addresses,each four octets long.Detailed information about networks within the corporatenetwork, so it can forward inbound packets correctly and onlysingle router is represented over internet. 7. Default router in IPIn IP, the default route is also known as the default gateway orthe gateway of last resort.The default route is represented using a special IP address (0.0.0.0)and subnet mask (0.0.0.0).In IP, routers and end stations use a simple rule when selecting aroute from the routing table: the best match wins.Eg: 192.14.17.0, 192.14.0.0, 192.0.0.0, and 0.0.0.0, and packetarrived destined for 192.14.17.23, the route associated with192.14.17.0 would be used. 8. Implementing the default routing.IP routing table, the default route can be placed there statically, orlearned dynamically.Typically entered statically by a network administrator in a routerthat connects by a single path to the broader internetwork. 9. Example Implementing the default routing. 10. Introduction On Demand Routing ProtocolA protocol used to discover other Cisco devices on either broadcastor non-broadcast media.With the help of CDP, it is possible to find the device type, the IPaddress, the Cisco IOS version running on the neighbour Ciscodevice, the capabilities of the neighbour device, and so on.ODR is able to carry Variable Length Subnet Mask (VLSM)information. 11. What is On Demand Routing Protocol?The routes are created when requiredThe source has to discover a route to the destination.The source and intermediate nodes have to maintain a route as longas it is used.Routes have to be repaired in case of topology changes. 12. On-Demand Routing Protocols1. Ad hoc On-demand Distance Vector Routing2. Dynamic Source Routing Protocol3. Temporally Ordered Routing Algorithm4. Associativity Based Routing 13. 1.Ad Hoc On-demand Distance VectorRoutingIncludes route discovery and route maintenance.Minimizes the number of broadcasts by creating routes on-demandUses only symmetric links because the route reply packet followsthe reverse path of route request packet.Uses hello messages to know its neighbors and to ensure symmeticlinks. 14. Example.sourceRREQThe node discards the packets having been seendestinationThe source broadcasts a route packetThe neighbors in turn broadcast thepacket till it reaches the destinationRREPReply packet follows the reverse path of routerequest packet recorded in broadcast packetaa 15. Route MaintenanceIf the source node moves, it reinitiates the routediscovery.If intermediate node moves, its upstream node sends aRREP to the source. The source restarts the routediscovery. 16. 2.Dynamic Source Routing ProtocolA node maintains route caches containing the routes itknows.Include route discovery and route maintenance. 17. Route discoveryThe source sends a broadcast packet which containssource address, destination address, request id and path.If a host saw the packet before, discards it.Otherwise, the route looks up its route caches to lookfor a route to destination, If not find, appends its addressinto the packet, rebroadcast, If finds a route in its route cache, sends a route replypacket, which is sent to the source by route cache or theroute discovery. 18. source broadcasts a packet containing address of source and destinationThe destination sends a reply packet to source.destinationsource1The node discards the packets having been seen6543287(1,4)(1,2)(1,3)(1,3,5) (1,3,5,6)(1,4,7)The route looks up its route caches to look for a route to destinationIf not find, appends its address into the packet 19. How to send a reply packet If the destination has a route to the source in itsroute cache, use itElse if symmetric links are supported, use thereverse of route recordElse if symmetric links are not supported, thedestination initiates route discovery to source 20. Route maintenance Whenever a node transmits a data packet, aroute reply, or a route error, it must verify thatthe next hop correctly receives the packet.If not, the node must send a route error to thenode responsible for generating this route headerThe source restart the route discovery 21. Add entries into route cache The Source and destination in route discoveryIntermediate hosts in route discoveryThe hosts receiving any broadcast 22. 3.Temporally Order RoutingAlgorithm Creating Routes: query/reply QRY packet is flooded through network UPD packet propagates back if route existMaintaining Routes: link-reversal UPD packets re-orient the route structureErasing Routes CLR packet is flood through network to erase invalid routes 23. The source broadcasts a QRY packet with height(D)=0, all others NULL(0,0,0,3,a) (0,0,0,2,d)aQRYOnly the non-NULL node (destination) responds with a UPD packet.fedcQRY QRYbhUPDg(-,-,-,-,d)(-,-,-,-,b)(-,-,-,-,c)(-,,-,-,-e) (-,-,-,-,f)(0,0,0,0,h)(-,-,-,-,a)(0,0,0,4,b)(0,0,0,4,c)(0,0,0,3,e) (0,0,0,2,f)sourceDest.((0-,,0-,,-0,,-1,g,g))A node receiving a UPD sets its height to one more than UPDSource receives a UPD with less height 24. TORA: Height metric Each node contains a quintuple Logical time of a link failure Unique ID of the node that defined the newreference level Reflection indicator bit A propagation ordering parameter, height Unique ID of the node 25. Route Maintenance and Erasing No reaction necessary if all nodes still have downstream links.A new reference level is defined if a node loses its last downstreamlink.Synchronized clock is important, accomplished via GPS oralgorithm such as Network Time Protocol.CLR packet to be flooded to clear the invalid packet. 26. afedcbhg(0,0,0,0,h)(0,0,0,4,b)(0,0,0,4,c)(0,0,0,3,e)(0,0,0,2,f)(0,0,0,3,a) (0,0,0,2,d)Dest.(0,0,0,1,g)Link failure with no reaction 27. Re-establishing route after link failureA new reference level is definedfed(1,d,0,-2,s) ((10,,d0,,00,,-31,a,a))cbhg(0,0,0,0,h)(0,0,0,4,b)(0,0,0,4,c)(0,0,0,3,e)(0,0,0,2,f)(0,0,0,2,d)0,0,0,4,s)Dest.(0,0,0,1,g)(1,d,0,0,d)UDPs aUDP 28. 4.Associativity Based Routing Each route keeps a associativity tableA high value of associativity tick indicates a lowstate of node mobilityA route is selected based on associativity states ofnodes, finds the high value of associativity tick(low mobility routes) 29. Associativity table All nodes generate periodic beaconsWhen a neighbor node receives a beacon, it increasesits associativity tick with respect to the sending nodein associativity tableAssociativity ticks are reset when the neighbors of anode or the node itself move out of proximity 30. Route Discovery The source broadcast a QRY messageEach intermediate node appends its address andassociativity ticks to QRY,The destination can examine the associativity ticks toselect route. If the multiple paths have the sameoverall degree of stability, select the minimumnumber of hops 31. Route Erasing If the the route is no longer desired, the source maynot be aware of any route node changes becausepartial reconstruction.The source node initiates a route delete (RD)broadcast to erase the invalid route. 32. ConclusionDefault Routing: Is configured for unknown destinations.Generally used on internet as destinations are unknown.Configured at end points.It is last preferred routing. 33. Conclusion Contin.On-Demand Routing:In On-Demand Routing the routes are created when required.The source and intermediate nodes have to maintain a route aslong as it is used.The source has to discover a route to the destination. 34. Bibilography http://www.hill2dot0.com/wiki/index.php?title=Default_route http://www.cisco.com/c/en/us/tech/ip/on-demand-routing-odr/index.html http://www.slideshare.net/kishoreeekumarrr/multi-static-routng-default-routing-29830267?v=default&b=&from_search=2 https://cs.wmich.edu/wsn/cs691_sp03/adhocrouting.ppt http://kiki.ee.ntu.edu.tw/mmnet1/adhoc/ 35. Q & A?